The Market Demand Curve for Mousetraps Is

The market demand curve for mousetraps is

A) found by summing the quantities of mousetraps demanded at each income level by each buyer.
B) found by summing the prices of mousetraps at each quantity of mousetraps demanded by each buyer.
C) the horizontal sum of the individual demand curves for mousetraps of all the buyers.
D) Both answers B and C are correct.
E) Both answers A and C are correct.